Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dietary deficiency of vitamin B-12 has been reported, yet most people ingesting vitamin-B12-deficient diets even for many years appear to achieve a balance that does not lead to overt signs and symptoms of deficiency. I present the case of a vegan of 25 years' duration who developed severe neurologic abnormalities due to vitamin-B12 deficiency. His diet provided 1.2 microgram of vitamin B12 daily at most. Despite normal Schilling test findings, he absorbed subnormal amounts of vitamin B12 given with ovalbumin. This poor absorption appeared to be related to his gastritis, achlorhydria, and subnormal intrinsic-factor secretion. Probably, vitamin-B12 deficiency in this patient resulted from both dietary restriction and the subtle malabsorption, neither of which would have sufficed alone to produce the clinical problem. Possibly such malabsorption may also be present in many of those vegans developing overt vitamin-B12 deficiency in whom Schilling test findings have been normal.
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PMID:Nutritional vitamin-B12 deficiency. Possible contributory role of subtle vitamin-B12 malabsorption. 64 50

1. Intestinal brush border enzymes have heterogeneous rates of turnover, the largest proteins having the fastest turnover. Since the membrane faces the intestinal lumen, the effects of pancreatic factors were examined in mediating this turnover. Surgical subtotal pancreatectomy was used as an experimental model to study the turnover of brush border proteins in the absence of most pancreatic secretions. 2. Subtotal (95%) pancreatectomy of rats was found to cause elevations by about 50% of total activity and specific activities of certain brush border enzymes (maltase, sucrase, lactase), but not of others (alkaline phosphatase, trehalase). Rats were judged to be functionally deficient in pancreatic proteolytic enzymes (a) by demonstration of vitamin B-12 malabsorption, which was corrected by trypsin, and (b) by the finding of only about 20% of proteolytic activity appearing in the lumen after a test meal when compared to control. 3. To measure protein turnover in vivo the method of double labelling was used, where [3H]- and [14C]valine were administered intraduodenally in sequence 10 h apart. With this technique, a high 3H/14C ratio is correlated with rapid turnover. Proteins with apparent molecular weights of about 200 000-270 000 were found to turn over more rapidly than smaller proteins. 3H/14C ranged from 4.7 to 6.2 in animals without pancreatic insufficiency. In the face of decreased pancreatic proteolysis, the 3H/14C ratio was 2.3-3.1, similar to that of proteins with a slow half life. 4. Estimates of relative synthetic rates of large brush border proteins were lower than normal in pancreatectomized animals, but were constant over the period of the labelling experiment. The high enzyme levels in the face of lower synthetic rates confirms that, at the new steady rate, degradation rates must be slower for large brush border proteins in pancreatic insufficiency. 5. In vitro, using purified brush borders, unfractionated pancreatic enzymes were found to remove sucrase, maltase and lactase, but not alkaline phosphatase and trehalase. The enzyme most potent in this respect was the pancreatic protease, elastase. Non-proteolytic enzymes (amylase, lipase, phospholipase A) were inactive in removing enzyme from the brush border. The addition of elastase to pancreatectomized animals in vivo restored the rapid turnover rate of large brush border proteins. 6. A model is thus proposed for the normal catabolism of some large intestinal brush border proteins. It is suggested that the surface of intestinal absorptive cells is being constantly remodelled, and that certain surface enzymes are in part removed from the membrane by the action of pancreatic proteases. A possible special role for elastase is suggested.
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PMID:The possible role of pancreatic proteases in the turnover of intestinal brush border proteins. 114 88

Vitamin B-12 deficiency was diagnosed in a 26-year-old man. Examinations performed to determine the etiology of the deficiency showed a vitamin B-12 malabsorption in the Schilling test which was corrected by adding intrinsic factor (IF) as well as normal gastric mucosa and acid secretion, although IF in gastric juice was absent. Family study showed normal serum vitamin B-12 levels in the parents, who are first cousins, and siblings. A gastric examination in the father and the sister showed decreased IF secretion, indicating heterozygosity for the disorder.
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PMID:Congenital intrinsic factor deficiency in a Spanish patient. 158 8

A prospective study of 60 consecutively admitted patients with HIV infection was performed to document the prevalence, etiology and manifestations of low serum vitamin B-12 in such patients. Low serum B-12 levels were found in 10 patients (16.7%). In 6, vitamin B-12 absorption was impaired and hog intrinsic factor addition did not improve it. Patients with low vitamin B-12 levels showed lower hemoglobin, leukocytes, lymphocytes, CD4 lymphocytes and CD4/CD8 lymphocyte ratio than HIV patients with physiological serum vitamin B-12 levels. However, bone marrow megaloblastosis was found in only 3 low vitamin B-12 patients and the deoxyuridine suppression test was pathological in only 1 case. In 7 patients, parenteral treatment was begun with variable response despite serum vitamin B-12 correction. In conclusion, low serum vitamin B-12 is often found in HIV-infected patients and it could be related to malabsorption, but clear megaloblastic abnormalities and treatment response could not be demonstrated. A decreased concentration of the serum binders due to disturbances in the leukocytes and related immunocompetent cell may play an additional role.
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PMID:Vitamin B-12 abnormalities in HIV-infected patients. 186 15

The occurrence of chronic diarrhoea was evaluated in 173 consecutive patients previously treated with radiation for gynaecological cancer. A survey of gastrointestinal symptoms showed a high frequency of diarrhoea; 13% of the patients had 21 or more bowel movements a week and 3% had 28 or more. Significantly more patients who had a cholecystectomy were in the group with diarrhoea (chi 2 = 6.26; p less than 0.02). Twenty patients with chronic or intermittent diarrhoea were subject to extended gastrointestinal investigation. Bile acid malabsorption was evaluated by the 75Selenahomocholic acid-taurine test (SeHCAT). Bile acid malabsorption was found in 13 (65%) of the 20 patients further investigated, of whom seven had extremely low whole body retention values, which is consistent with severe malabsorption. The results suggest that bile acid malabsorption is a common cause of diarrhoea after radiation treatment for gynaecological cancer. Bacterial contamination was diagnosed in nine patients (45%) by the [14C]-D-xylose breath test or by the cholyl-[14C]-glycine breath test in combination with a normal test for bile acid malabsorption. All patients with vitamin B-12 deficiency, who were tested for bile acid malabsorption, had low retention times for the SeHCAT (p = 0.05). A significant decline in the frequency of diarrhoea was found after treatment with antibiotics or bile acid sequestrants, or both, in combination with a reduced fat diet.
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PMID:Chronic diarrhoea after radiotherapy for gynaecological cancer: occurrence and aetiology. 195 74

We have previously reported our efforts to minimize postgastrectomy symptoms in two patients with benign disease who underwent resection of the head of the pancreas and the duodenum. In these cases the pylorus and first portion of the duodenum were preserved during pancreaticoduodenectomy. Our experience has now been extended to encompass 18 patients, eight of whom were available for comprehensive evaluation an average of six months postoperation. These studies have attempted to differentiate malabsorption of pancreatic insufficiency from possible gastrointestinal dysfunction of the new alimentary connection. Pancreatic insufficiency was evaluated by a 72-hour stool collection and radioactive trioctanoate (RATO) test. Gastrointestinal absorption was evaluated by D-xylose excretion and the Schilling test, as well as serum vitamin. A, vitamin B-12, carotene, folate, iron, and total iron binding capacity. Gastrointestinal secretion and motility were assessed by using pyloric fluoroscopy, gastric barium emptying, the Hunt test, and gastric acid analysis. Finally, a questionnaire regarding clinical symptoms of postgastrectomy syndromes and malabsorption was answered. Although every patient exhibited marked pancreatic insufficiency by laboratory tests, 88% described normal formed bowel movements, and weight loss was claimed by only 25%. Other test findings were generally normal. While the follow-up period has been limited to three years, the current data demonstrate that gastrointestinal function subsequent to preservation of the pylorus has not thus far predisposed to postgastrectomy syndromes or marginal ulcers. All of the patients required intensive pancreatic enzyme replacement.
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PMID:Preservation of the pylorus in pancreaticoduodenectomy a follow-up evaluation. 741 28

Vitamin B-12 status of rural Mexicans was evaluated in two studies, 6 y apart. In the first, a single blood sample was collected from children and adults, including pregnant and lactating women. Prevalence of deficient plasma vitamin B-12 values ranged from 19% to 41% among groups, but plasma folate status was normal in all individuals. Breast milk vitamin B-12 concentration was low in 62% of samples. The second study was conducted in 219 children aged 18-36 mo in five communities, whose prevalence of deficient and low plasma vitamin B-12 concentrations, respectively, was 8% and 33% on entry, 3% and 22% 6 mo later, and 7% and 29% 12 mo later. Prevalence of low holotranscobalamin II concentrations, indicating malabsorption of the vitamin, averaged 18-40% across the three same periods. Both vitamin B-12 status indicators differed significantly between communities. The widespread vitamin B-12 deficiency was probably caused by malabsorption, perhaps exacerbated by low dietary intake and, for young children, maternal depletion of the vitamin.
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PMID:Vitamin B-12 deficiency and malabsorption are highly prevalent in rural Mexican communities. 757 25

We evaluated the association of moderate hyperhomocyst(e)inemia and vitamin B-12 status with coronary artery disease (CAD) and left ventricular ejection fraction in 367 elderly patients undergoing coronary angiography. The extent of CAD was scored, left ventricular ejection fraction was assessed and vitamins B-12 and folate and the metabolites homocyst(e)ine, methylmalonic acid and 2-methylcitric acid were measured. There was no significant trend in change in homocyst(e)ine as the extent of CAD increased. There was an association between vitamin B-12 deficiency, i.e., vitamin B-12 < 221 pmol/l and homocyst(e)ine > 16 nmol/ml and low left ventricular ejection fraction (P = 0.014). Of 105 samples, selected for vitamin B-12 < 221 pmol/l or high normal vitamin B-12 and folate levels, metabolites including methylmalonic acid revealed a specific diagnosis of vitamin B-12 deficiency in 18 patients. The trend among these vitamin B-12-deficient patients and low left ventricular ejection fraction was significant (P = 0.028). In vitro studies on rat heart revealed that nitrous oxide in the presence of 200 microM/l methionine reduced contractility of the heart. In conclusion, vitamin B-12-deficient patients had significantly lower left ventricular ejection fractions than nonvitamin B-12-deficient patients. Whether low left ventricular ejection fraction results in malabsorption of vitamin B-12 and vitamin B-12 deficiency, or conversely, whether vitamin B-12 and its marker, elevated homocyst(e)ine, depress left ventricular function warrants further evaluation.
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PMID:Relationship among homocyst(e)ine, vitamin B-12 and cardiac disease in the elderly: association between vitamin B-12 deficiency and decreased left ventricular ejection fraction. 864 65

This study evaluated vitamin B-12 status in 113 Guatemalan women and their infants at 3 months of lactation. Findings revealed that plasma vitamin B-12 was deficient or low in 46.7% of the mothers and that holotranscobalamin II (holo TC II) concentrations were low in 32.3%, which may indicate vitamin B-12 malabsorption. Only 9% had deficient or low plasma folate. Breast milk vitamin B-12 was low in 31% and negatively correlated with infant urinary methylmalonic acid (UMMA). UMMA was elevated in 12.2% of the infants, indicating vitamin B-12 deficiency. Mothers of the infants with elevated UMMA had significantly lower concentrations of vitamin B-12 in their breast milk compared with mothers of infants with normal UMMA concentrations. Mean maternal dietary intake of vitamin B-12 was significantly correlated with plasma vitamin B-12 and was the main determinant of plasma vitamin B-12 in a linear regression model. Determinants of maternal holo TC II concentrations included dietary intake of vitamin B-12 and Giardia lamblia infection. There were no statistically significant determinants of infant UMMA concentrations. This study concludes that vitamin B-12 deficiency is highly prevalent in these lactating women and is associated with the depletion of the vitamin in their infants. The cause of the maternal deficiency is unknown, but malabsorption, exacerbated by low dietary intake of the vitamin, is a possibility.
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PMID:Vitamin B-12 deficiency is very prevalent in lactating Guatemalan women and their infants at three months postpartum. 931 52

In response to research findings that 10% to 30% of people aged 51 years and older may have protein-bound vitamin B-12 malabsorption, the National Academy of Sciences' Institute of Medicine recommends that these people consume a majority of the new Recommended Dietary Allowance (RDA) of 2.4 micrograms/day in its synthetic form rather than in its food form. Protein-bound vitamin B-12 malabsorption in older adults has been attributed to reduced pepsin activity and gastric acid secretion, which interfere with cleavage of vitamin B-12 from dietary protein before absorption. Unlike patients with pernicious anemia, most people with protein-bound vitamin B-12 malabsorption produce intrinsic factor and have the ability to absorb synthetic vitamin B-12 normally. Early diagnosis is necessary to prevent the untoward effects of vitamin B-12 deficiency. A thorough assessment of vitamin B-12 status entails measurement of multiple biochemical assessment indexes, including serum vitamin B-12, methylmalonic acid, and homocysteine concentrations. Dietitians and other health care professionals should be aware of the prevalence of vitamin B-12 deficiency in older adults and be familiar with sources of synthetic vitamin B-12 to facilitate implementation of the new RDA.
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PMID:Practitioners' guide to meeting the vitamin B-12 recommended dietary allowance for people aged 51 years and older. 1036 36


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